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<i class='fas fa-caret-right ms-1'></i></div><div id=sidebar-toc class="hidden md:block overflow-y-auto mx-6 md:mx-0 pe-6 pt-2 md:max-h-doc-sidebar bg-primary-bg md:bg-transparent"><div class="flex flex-wrap ms-4 -me-2 p-2 bg-secondary-bg md:bg-primary-bg rounded"><a class=hover:text-eureka href=https://b.hui.ke/docs/python/>Python</a></div><ul class=ps-6><li class=py-2><div><a class=hover:text-eureka href=https://b.hui.ke/docs/python/20/>期末测验</a></div></li><li class=py-2><div><a class=hover:text-eureka href=https://b.hui.ke/docs/python/10/>【第9+周笔记】全课程总结与学习展望</a></div></li><li class=py-2><div><a class=hover:text-eureka href=https://b.hui.ke/docs/python/19/>【第9周程序】计算生态纵览</a></div></li><li class=py-2><div><a class=hover:text-eureka href=https://b.hui.ke/docs/python/9/>【第9周笔记】计算生态纵览</a></div></li><li class=py-2><div><a class=hover:text-eureka href=https://b.hui.ke/docs/python/18/>【第8周程序】程序设计方法学</a></div></li><li class=py-2><div><a class=hover:text-eureka href=https://b.hui.ke/docs/python/8/>【第8周笔记】程序设计方法学</a></div></li><li class=py-2><div><a class="text-eureka hover:text-eureka" href=https://b.hui.ke/docs/python/17/>【第7周程序】文件和数据格式化</a></div></li><li class=py-2><div><a class=hover:text-eureka href=https://b.hui.ke/docs/python/7/>【第7周笔记】文件和数据格式化</a></div></li><li class=py-2><div><a class=hover:text-eureka href=https://b.hui.ke/docs/python/16/>【第6周程序】组合数据类型</a></div></li><li class=py-2><div><a class=hover:text-eureka href=https://b.hui.ke/docs/python/6/>【第6周笔记】组合数据类型</a></div></li><li class=py-2><div><a class=hover:text-eureka href=https://b.hui.ke/docs/python/15/>【第5周程序】函数和代码复用</a></div></li><li class=py-2><div><a class=hover:text-eureka href=https://b.hui.ke/docs/python/5/>【第5周笔记】函数和代码复用</a></div></li><li class=py-2><div><a class=hover:text-eureka href=https://b.hui.ke/docs/python/14/>【第4周程序】程序的控制结构</a></div></li><li class=py-2><div><a class=hover:text-eureka href=https://b.hui.ke/docs/python/4/>【第4周笔记】程序的控制结构</a></div></li><li class=py-2><div><a class=hover:text-eureka href=https://b.hui.ke/docs/python/13/>【第3周程序】基本数据类型</a></div></li><li class=py-2><div><a class=hover:text-eureka href=https://b.hui.ke/docs/python/3/>【第3周笔记】基本数据类型</a></div></li><li class=py-2><div><a class=hover:text-eureka href=https://b.hui.ke/docs/python/12/>【第2周程序】Python 基本图形绘制</a></div></li><li class=py-2><div><a class=hover:text-eureka href=https://b.hui.ke/docs/python/2/>【第2周笔记】Python 基本图形绘制</a></div></li><li class=py-2><div><a class=hover:text-eureka href=https://b.hui.ke/docs/python/11/>【第1周程序】Python 基本语法元素</a></div></li><li class=py-2><div><a class=hover:text-eureka href=https://b.hui.ke/docs/python/1/>【第1周笔记】Python 基本语法元素</a></div></li></ul></div></div></div><div class="w-full md:w-3/4 lg:w-4/5 pb-8 pt-2 md:pt-8"><div class=flex><div class="w-full lg:w-3/4 px-6"><article class=prose><h1 class=mb-4>【第7周程序】文件和数据格式化</h1><div class="text-tertiary-text not-prose mt-2 flex flex-row flex-wrap items-center"><div class="me-6 my-2"><i class="fas fa-calendar me-1"></i>
<span>2022-05-03</span></div><div class="me-6 my-2"><i class="fa-solid fa-pen-to-square me-1"></i>
<span>2022-05-03</span></div><div class="me-6 my-2"><i class="fas fa-clock me-1"></i>
<span>3 min read</span></div><div class="me-6 my-2"><i class="fas fa-folder me-1"></i>
<a href=https://b.hui.ke/categories/it/ class=hover:text-eureka>IT</a></div><div class="me-6 my-2"><i class="fas fa-th-list me-1"></i>
<a href=https://b.hui.ke/series/python/ class=hover:text-eureka>Python</a></div><div class="me-6 my-2"><i class="fa-solid fa-eye me-1"></i>
<span id=busuanzi_value_page_pv><i class="fa fa-spinner fa-spin"></i></span> Hits</div></div><p>  程序设计练习题和考试题</p><h2 id=文件行数>文件行数</h2><p>打印输出附件文件的有效行数，注意：空行不计算为有效行数。</p><h3 id=参考答案>参考答案</h3><pre><code class=language-python>f = open(&quot;latex.log&quot;)
s = 0
for line in f:
    line = line.strip('\n')
    if len(line) == 0:
        continue
    s += 1
print(&quot;共{}行&quot;.format(s))
</code></pre><h3 id=答案解析>答案解析</h3><p>需要注意：for line in f 方式获得的每行内容（在变量 line 中）包含换行符，所以，要通过 strip() 函数去掉换行符后再进行统计。这里，空行指没有字符的行。</p><h3 id=最优解>最优解</h3><pre><code class=language-python>f = open(&quot;latex.log&quot;)
s = 0
for line in f:
    line = line.strip('\n')
    if len(line) != 0:
        s += 1
print(&quot;共{}行&quot;.format(s))
</code></pre><h2 id=文件字符分布>文件字符分布</h2><p>统计附件文件的小写字母 a-z 的字符分布，即出现 a-z 字符的数量，并输出结果。</p><p>同时请输出文件一共包含的字符数量。</p><p>注意输出格式，各元素之间用英文逗号（,）分隔。</p><p>答案可能包含 a-z 共 26 个字符的分布，如果某个字符没有出现，则不显示，输出顺序 a-z 顺序。</p><h3 id=参考答案-1>参考答案</h3><pre><code class=language-python>f = open(&quot;latex.log&quot;)
cc = 0
d = {}
for i in range(26):
    d[chr(ord('a')+i)] = 0
for line in f:
    for c in line:
        d[c] = d.get(c, 0) + 1
        cc += 1
print(&quot;共{}字符&quot;.format(cc), end=&quot;&quot;)
for i in range(26):
    if d[chr(ord('a')+i)] != 0:
        print(&quot;,{}:{}&quot;.format(chr(ord('a')+i), d[chr(ord('a')+i)]), end=&quot;&quot;)
</code></pre><h3 id=答案解析-1>答案解析</h3><p>使用 ord(&lsquo;a&rsquo;)+i 配合 range() 函数 可以遍历一个连续的字符表。</p><h2 id=文件独特行数>文件独特行数</h2><p>统计附件文件中与其他任何其他行都不同的行的数量，即独特行的数量。</p><h3 id=参考答案-2>参考答案</h3><pre><code class=language-python>f = open(&quot;latex.log&quot;)
ls = f.readlines()
s = set(ls)
for i in s:
    ls.remove(i)
t = set(ls)
print(&quot;共{}独特行&quot;.format(len(s)-len(t)))
</code></pre><h3 id=答案解析-2>答案解析</h3><p>记住：如果需要"去重"功能，请使用集合类型。</p><p>ls.remove() 可以去掉某一个元素，如果该行是独特行，去掉该元素后将不在集合t中出现。</p><h3 id=最优解-1>最优解</h3><pre><code class=language-python>f = open(&quot;latex.log&quot;)
ls = f.readlines()
s = set(ls)
for i in s:
    ls.remove(i)
print(&quot;共{}独特行&quot;.format(len(s)-len(set(ls))))
</code></pre><h2 id=csv-格式列变换>CSV 格式列变换</h2><p>附件是一个 CSV 文件，请将每行按照列逆序排列后输出，不改变各元素格式（如周围空格布局等）。</p><h3 id=参考答案-3>参考答案</h3><pre><code class=language-python>f = open(&quot;data.csv&quot;)
for line in f:
    line = line.strip(&quot;\n&quot;)
    ls = line.split(&quot;,&quot;)
    ls = ls[::-1]
    print(&quot;,&quot;.join(ls))
f.close()
</code></pre><h3 id=最优解-2>最优解</h3><pre><code class=language-python>f = open(&quot;data.csv&quot;)
for line in f:
    line = line.strip(&quot;\n&quot;)
    print(&quot;,&quot;.join(line.split(&quot;,&quot;)[::-1]))
f.close()
</code></pre><h2 id=csv-格式数据清洗>CSV 格式数据清洗</h2><p>附件是一个 CSV 文件，其中每个数据前后存在空格，请对其进行清洗，要求如下：</p><ol><li>去掉每个数据前后空格，即数据之间仅用逗号（,）分割；</li><li>清洗后打印输出。</li></ol><h3 id=参考答案-4>参考答案</h3><pre><code class=language-python>f = open(&quot;data.csv&quot;)
s = f.read()
s = s.replace(&quot; &quot;,&quot;&quot;)
print(s)
f.close()
</code></pre><h3 id=答案解析-3>答案解析</h3><p>该 CSV 文件的每个数据中不包含空格，因此，可以通过替换空格方式来清洗。如果数据中包含空格，该方法则不适用。</p><h3 id=最优解-3>最优解</h3><pre><code class=language-python>f = open(&quot;data.csv&quot;)
print(f.read().replace(&quot; &quot;,&quot;&quot;))
f.close()
</code></pre><h2 id=文本的平均列数>文本的平均列数</h2><p>打印输出附件文件的平均列数，计算方法如下：</p><ol><li>有效行指包含至少一个字符的行，不计算空行；</li><li>每行的列数为其有效字符数；</li><li>平均列数为有效行的列数平均值，采用四舍五入方式取整数进位</li></ol><h3 id=参考答案-5>参考答案</h3><pre><code class=language-python>f = open(&quot;latex.log&quot;)
s, c = 0, 0
for line in f:
    line = line.strip(&quot;\n&quot;)
    if line == &quot;&quot;:
        continue
    s += len(line)
    c += 1
print(round(s/c))
</code></pre><h3 id=答案解析-4>答案解析</h3><p>请注意：for line in f 获取的 line 包含每行最后的换行符（\n），所以，去掉该换行符进行统计。</p><h2 id=csv-格式清洗与转换>CSV 格式清洗与转换</h2><p>附件是一个 CSV 格式文件，提取数据进行如下格式转换：</p><ol><li>按行进行倒序排列；</li><li>每行数据倒序排列；</li><li>使用分号（;）代替逗号（,）分割数据，无空格；</li></ol><p>按照上述要求转换后将数据输出。</p><h3 id=参考答案-6>参考答案</h3><pre><code class=language-python>f = open(&quot;data.csv&quot;)
ls = f.readlines()
ls = ls[::-1]
lt = []
for item in ls:
    item = item.strip(&quot;\n&quot;)
    item = item.replace(&quot; &quot;, &quot;&quot;)
    lt = item.split(&quot;,&quot;)
    lt = lt[::-1]
    print(&quot;;&quot;.join(lt))
f.close()
</code></pre><h3 id=答案解析-5>答案解析</h3><p>注意：使用 strip() 方法去掉每行最后的回车，使用 replace() 去掉每行元素两侧的空格。</p><h3 id=最优解-4>最优解</h3><pre><code class=language-python>f = open(&quot;data.csv&quot;)
lines = f.readlines()
lines.reverse()
for line in lines:
    line = line.strip(&quot;\n&quot;)
    line = line.replace(' ','')
    t = line.split(&quot;,&quot;)
    t.reverse()
    print(&quot;;&quot;.join(t))
</code></pre></article><div class=my-4><a href=https://b.hui.ke/tags/program/ class="inline-block bg-tertiary-bg text-sm rounded px-3 py-1 my-1 me-2 hover:text-eureka">#Program</a></div><div class=py-2><div class="my-8 flex flex-col items-center md:flex-row"><a href=https://b.hui.ke/authors/hui.ke/ class="md:me-4 text-primary-text h-24 w-24"><img src=https://b.hui.ke/bagua.webp class="bg-primary-bg w-full rounded-full" alt=Avatar></a><div class="mt-4 w-full md:mt-0 md:w-auto"><a href=https://b.hui.ke/authors/hui.ke/ class="mb-2 block border-b pb-1 text-lg font-bold"><h3>Hui.Ke</h3></a><span class="block pb-2">❤ Cyber Security | Safety is a priority.</span>
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hidden px-6 pb-6 lg:block"><nav id=TableOfContents><ul><li><a href=#文件行数>文件行数</a><ul><li><a href=#参考答案>参考答案</a></li><li><a href=#答案解析>答案解析</a></li><li><a href=#最优解>最优解</a></li></ul></li><li><a href=#文件字符分布>文件字符分布</a><ul><li><a href=#参考答案-1>参考答案</a></li><li><a href=#答案解析-1>答案解析</a></li></ul></li><li><a href=#文件独特行数>文件独特行数</a><ul><li><a href=#参考答案-2>参考答案</a></li><li><a href=#答案解析-2>答案解析</a></li><li><a href=#最优解-1>最优解</a></li></ul></li><li><a href=#csv-格式列变换>CSV 格式列变换</a><ul><li><a href=#参考答案-3>参考答案</a></li><li><a href=#最优解-2>最优解</a></li></ul></li><li><a href=#csv-格式数据清洗>CSV 格式数据清洗</a><ul><li><a href=#参考答案-4>参考答案</a></li><li><a href=#答案解析-3>答案解析</a></li><li><a href=#最优解-3>最优解</a></li></ul></li><li><a href=#文本的平均列数>文本的平均列数</a><ul><li><a href=#参考答案-5>参考答案</a></li><li><a href=#答案解析-4>答案解析</a></li></ul></li><li><a href=#csv-格式清洗与转换>CSV 格式清洗与转换</a><ul><li><a href=#参考答案-6>参考答案</a></li><li><a href=#答案解析-5>答案解析</a></li><li><a href=#最优解-4>最优解</a></li></ul></li></ul></nav></div><script>window.addEventListener("DOMContentLoaded",()=>{enableStickyToc()})</script></div></div></div></div></div><script>document.addEventListener("DOMContentLoaded",()=>{hljs.highlightAll(),changeSidebarHeight(),switchDocToc()})</script></div></div></main><footer class=pl-scrollbar><div class="mx-auto w-full max-w-screen-xl"><div class="text-center p-6 pin-b"><script async src=/js/click.js></script><div id=poem_ip></div><script type=text/javascript>jinrishici.load(function(e){tags.innerHTML=e.data.matchTags})</script><div><span id=timeDate>载入年天数...</span><span id=times>载入时分秒...</span>
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